Prior to the issuance of the Conway et al. patent (U.S. Pat. No. 4,475,910) (reexamined and reissued as U.S. Pat. No. RE 33,206 on May 1, 1990), external male urinary catheters or condom catheters were generally retained on a penis of an incontinent male with an adhesive tape of one type or another.
The adhesive coated catheter disclosed by Conway et al. provided incontinent males with a self-sealing external catheter which required no tapes, was easier to put on, and had functional advantages over prior art catheters, such as reduced leakage due to the improved seal between the catheter and the penis. The "strapless" catheter of Conway et al. has proven to be a great commercial success and has become the catheter of choice for many men who are incontinent and must wear an external urinary catheter.
Similar strapless catheters have been disclosed in subsequent patents (e.g. U.S. Pat. Nos. 4,581,026; 4,863,449; 4,769,099; 4,846,909; and 4,885,049). Each of the aforementioned patents, including the Conway et al. patent, disclose external catheters which provide a construction having at least three distinct layers, namely an adhesive layer, an elastomeric sheath, and a release layer. In each case, the respective inventors have devised devices which insure that when the elastomeric sheath is "rolled up" in a pre-use storage orientation, the adhesive layer is sandwiched between an inner surface of the elastomeric sheath and an outer surface of the elastomeric sheath, with the release layer interposed between the adhesive layer and the outer surface.
The release layer has been critical to the aforementioned catheters because it is very important to enable the adhesive layer to separate from the outer surface of the elastomeric sheath when the condom catheter is unrolled onto the penis of the user. If the adhesive layer sticks to the outer surface of the elastomeric sheath when it is in the "rolled up" pre-use orientation, which it will if the sheath is made of latex, the catheter will be difficult to apply and unacceptable in the marketplace. Thus, the prior inventors have been very concerned with providing a release layer which will "release" the adhesive from the outer surface of the elastomeric sheath such that the adhesive layer remains bonded only to the inner surface of the sheath and is subsequently able to stick to the external surface of the penis so as to provide for effective retention of the catheter thereon. It will be appreciated that each of the aforementioned patents disclose the concept of laminating either the outer surface of the catheter or the exposed surface of the adhesive layer in order to provide for the release layer and to allow the catheter to work in the manner described above.
The Conway et al. patent discloses a catheter including an elastomeric sheath having a release layer on an outer surface thereof and an adhesive material sandwiched between the release layer and the inner surface of the elastomeric sheath when the inner surface is rolled up upon the outer surface and the release layer in the pre-use orientation.
Johannesson (U.S. Pat. No. 4,885,049) discloses a slightly different approach for providing a similar device. Schneider (U.S. Pat. No. 4,581,026) discloses two means of securing an external catheter to a penis. One requires the use of an adhesive pad or tape, and the other requires the use of an adhesive band on an inner surface of the sheath which will not bond to an outer surface thereof because the outer surface is coated with a "suitable elastomeric agent" such as silicone rubber.
Riedel et al. (U.S. Pat. No. 4,589,874) also disclose a catheter having an adhesive on an inner surface of an elastomeric sheath which is in contact with release material on the outer surface of the elastomeric sheath. The adhesive is released from a release material when the catheter is unrolled onto a penis. Schneider (U.S. Pat. No. 4,676,250) and Klug et al. (U.S. Pat. No. 4,846,909) also disclose similar adhesive means.
It will be appreciated from a detailed review of the aforementioned patents, that constructing these "layered" catheters can be quite difficult. Each requires means for constructing a catheter including three "layers". These three layers are the adhesive layer, the elastomeric sheath, and the release layer which allows the adhesive layer to be rolled up upon the outer surface of the elastomeric sheath such that the release layer is interposed between the adhesive layer and the outer surface thereof, thus enabling a user to easily unroll the elastomeric sheath onto the user's penis without undo difficulty resulting from substantial adhesion between the adhesive layer and the outer surface.
In actual practice, it is believed that each of the aforementioned inventions have an elastomeric sheath made of a latex material. The adhesive layer is generally a band of pressure sensitive adhesive, and the release layer generally consists of silicone rubber, to which the pressure sensitive adhesive will not bond. The prior art catheters each function because the adhesive will bond to the latex sheath, but will not bond to the silicone rubber release layer. Thus, when the catheter is rolled up into the pre-use orientation, each of the aforementioned prior art catheters consist of a latex sheath, coated on the outside with a silicone rubber "release" layer, with a band of adhesive material sandwiched between an inner latex surface, to which the adhesive is bound, and an outer silicone rubber surface interposed between the outer latex surface and the adhesive material. When the catheter is unrolled, the adhesive will stick only to the latex surface while releasing from the silicone rubber surface.
In addition to being fairly difficult to manufacture, these multi-laminated catheters have a number of important drawbacks. One of the most important drawbacks is the fact that latex materials contain leachable chemical constituents which can cause a wide range of skin reactions. This problem is especially accentuated in aqueous environments, often created with the presence of urine. It will be appreciated that latex catheters will absorb aqueous fluids such as urine and become wetted, thereby enhancing the opportunity for leachates to irritate the user's skin. Because many patients have to wear these catheters continuously, the risk of irritating the skin is quite significant.
Leachates found in latex may also "bloom" on the surface of the adhesive material when the catheter is in storage, thus weakening the adhesive bond which might otherwise be possible between the catheter and the penis when the catheter is applied thereto.
The aforementioned urinary catheters also have other significant problems, such as delamination of the release layer and the elastomeric sheath during storage; the unattractive "old rubber" smell characteristic of latex products which have been stored for a significant period of time; the resistance to the passage of light through the latex sheath which limits ones ability to view the condition of the penis through the opaque latex sheath; and the use of powders on the surface of the latex sheath which tend to interfere with the adhesion between the adhesive layer and the penis.
It will be appreciated, therefore, that there are significant problems with the prior art external catheters and the methods for making the same. The present invention provides advantages over the prior art catheters and over the prior art methods for manufacturing such catheters, and also offers other advantages over the prior art and solves other problems associated therewith.